Thursday 16 June 2011 02.00 EDT
First published on Thursday 16 June 2011 02.00 EDT

Kate and William, Petrarch and Laura, cod and chips: fish and potatoes are up there with the world's greatest love stories. Rice is nice – think paella, or kedgeree – but this is one of those rare and beautiful unions where both parties shine brighter in each other's company: from poached salmon and Jersey royals to Jansson's temptation and cullen skink, the combination just works. Fishcakes are the perfect example of a marriage of convenience which has become far more than the sum of its leftover parts - they exude a solid charm which belies their eminently thrifty origins.

I've long been a secret fan of those day-glo curling stones which spend all day drying out under chip shop heat lamps, cheek by jowl with the savs and cheese pies, but I really fell in love with the fish cake when a far worldlier boyfriend whisked me off to lunch at Le Caprice for my 18th birthday. Dame Judi Dench was there, her words muffled by an impossibly thick carpet, but even the presence of M at the next table couldn't distract me from the luxuriously-sized fishcake in a pool of piquant sorrel sauce that was set before my callow teenage self that afternoon. I was sold – on posh restaurants, cream carpets and, most of all, fishcakes containing actual seafood.

The fish

In theory, your choice of fish with such a dish is entirely dependent on your leftovers – fishcakes are, as we will see, very flexible things (well, until you try to keep them together in the pan, that is). Such is the essential genius of the recipe, however, that it's quite acceptable to cook some specially – but what kind? Crab is of course the classic across the pond, but the price of crustaceans being what it is here, I'm assuming that you'll probably want to opt for fish instead.

Simon Hopkinson and Lindsay Bareham preface their recipe in The Prawn Cocktail Years by explaining that the "British tradition is with cod, sometimes haddock and, after a salmon with mayonnaise, a 'luxury' version", adding that this is "ironic" given that cod is now "more expensive than (farmed) salmon". I find their 100% salmon version heavy rather than luxurious though – the fish is just too meaty for the purpose, however nice the same thing was for a treat at Le Caprice.

Hugh Fearnley-Whittingstall and Nick Fisher use smoked mackerel in the Fish Book, which is a new one on me, although I often include a little smoked haddock in my mix. It has the advantage of coming ready cooked, ready to fold into mashed potato, but although the flavour combination is good, frying an oily fish like mackerel makes the cakes rather greasy, and although I don't season the mix, they're still very salty.

Angela Nilsen uses cod or haddock in her ultimate fishcakes – and although they're lovely and fluffy I find them ever-so slightly dry in texture after the others: a combination of fish, I conclude, offers the best of all worlds.

The spuds

It goes without saying that you need a fluffy mash for this – the lovely waxy new potatoes available at this time of year are too dense to hold together in a cake. As every canny cook knows, perfectly good fishcakes can be made from leftover mash, but Hugh and Nick make some specifically for the purpose, adding 50g butter to the pan. The recipe from Le Caprice, as well as that of gastropub queen Trish Hilferty (who has written an entire book in celebration of the union of fish and potato, Lobster and Chips) calls for potatoes mashed until smooth without butter or milk, and Simon and Lindsay keep things even simpler and crush them with a fork.

I find the buttery mash makes the finished fishcakes too soft – even after chilling, it's difficult to get them into the pan in one piece, something which also applies to Trish's use of melted butter rather than beaten egg as a binding. The plain mash, dried out in a hot pan before use, is easier to handle, but the chunks in Simon and Lindsay's roughly crushed potatoes mean their fishcakes have by far the most interesting texture.

The binding

Having established that beaten egg trumps melted butter in the firm fishcake stakes, I'm sceptical of the use of double cream and egg yolk in the Prawn Cocktail Years recipe – that, surely, takes the dish into dinner party territory, rather than the Sunday supper at which it properly belongs. Not only does it make the mix slightly too damp for easy moulding, but it seems to dull the flavours slightly – cream and salmon might be fine for the rarefied environs of Le Caprice, but I want something snappier in my repertoire.

The coating

Simon and Lindsay coat their fishcakes in flour, rather than the more traditional egg and breadcrumbs, while Nigella uses matzo meal. I find both of these, however, lack the satisfying crunch that makes such a pleasing contrast to the soft, savoury starchiness within – or maybe I'm just nostalgic for the chippie.

Spud you don't like?

Just as I think I'm whittling down my options, a chance flick through Nigel Slater's Kitchen Diaries yields a potato-less version, which mixes salmon, dill, flour, mustard and egg white together to make "tiny cakes that crisp up in the pan and weigh less heavily on the stomach than the traditional variety". They're more like fritters really – crunchy and delicious, but ultimately rather unsatisfactory: even Nigel admits that "despite a side dish of green beans and parsley, they leave us in need of a pudding".

Flavour of the month

Angela Nilsen fishcakes. Photograph: Felicity Cloake for the Guardian

One of the beauties of the fishcake is how easy it is to play around with: once you've tailored the basics to your satisfaction, the choice of icing on this particular cake is very much up to you. Horseradish and mustard, although popular with the likes of Nigel, Hugh and Angela, seem to me to miss the point of the dish – the very blandness of the potato is vital for offsetting the other flavours, so I prefer to add solid ingredients instead.

Hardboiled eggs, as used by Simon and Lindsay, make the mixture too crumbly, but, thinking laterally along the lines of a classic tartare sauce that so often accompanies fish, I've added capers for a salty hit along with some finely chopped anchovies, rather than the anchovy essence suggested in the Prawn Cocktail Years. Gherkins, I discover, are a step too far down this road however: like Nigel Slater's dill, they're just too sweet for my taste. After trying out both spring onions and parsley I decide that the subtler flavour of chives works better: the hot pepperiness of both ingredients is a distraction from the soothing, salty potatoey-ness of the dish.

Perfect fishcakes

Savoury, crisp and starchy, fishcakes are not a particularly sophisticated pleasure, wherever you eat them, so keep things simple with plain potato, a mix of fish, and a couple of zesty flavourings. Sorrel sauce and Judi Dench are entirely optional.

1. Peel the potatoes and cut into evenly sized chunks. Put into a large pan and cover with cold water. Add a generous pinch of salt and bring to the boil, then turn down the heat slightly and simmer until tender, but not mushy. Drain and put back into the hot pan for a minute to dry off, then roughly crush them with a fork, so they're a mixture of mash and larger lumps.

2. Meanwhile, put the fish into a large pan and just cover with water. Bring to a simmer, then gently cook for 3–5 minutes, depending on the size of the fillets, until the skin, if any, pulls off easily, and it's just beginning to flake. Drain, skin if necessary and set aside to cool, then break into large flakes and add to the potatoes.

3. Stir in the chives, capers and anchovies. Season lightly, and mix together gently, adding a little of the beaten egg to bring the mixture together into patties – it shouldn't be too sloppy. Use your hands to form into four large cakes or six smaller ones.

4. Put the remaining egg in a shallow bowl, and tip the flour and breadcrumbs on to separate saucers. Dip each fishcake in turn into the flour, the egg, and finally the breadcrumbs until thoroughly coated. Put into the fridge for at least half an hour to firm up.

5. Heat a frying pan with the butter and oil until the butter begins to foam. Add the fishcakes, in batches if necessary, cook for 5 minutes on a medium-high heat until golden and well crusted, then turn them carefully over and repeat on the other side.

What's the secret of your fishcakes, and does anyone have any top tips for keeping them together in the pan? Are they the best leftover mash can aspire to, or do you have another favourite fish and potato combination up your sleeve?